1. Field of the Invention
The present invention relates to a combined transport and gate assembly for a document storage and retrieval system and, more particularly, to a simplified transport and gate assembly which minimizes the number of storage compartments required in a document storage and retrieval system for transferring card holding cartridges from a receiving station into the storage system.
2. Description of the Prior Art
Due to the widespread practice of storing information on cards, as, for example, aperture cards, tabulating cards, microfiches and the like, the principles of the present invention will be described with respect to a storage and retrieval system designed for use with cards. Of course, it is to be understood that although the present invention possesses a high degree of utility in systems in which the storage medium takes the form of a card, the principles of this invention are also applicable to systems in which the documents are of a nature other than cards. For example, it is contemplated that the principles of the present invention may be used in systems in which the documents take the form of ledger sheets, engineering drawings, legal documents, photographs, maps, and the like.
The desirability of mechanizing card storage and retrieval has been appreciated for many years. Mechanization permits cards to be obtained from storage more quickly than is ordinarily possible using conventional, manual retrieval techniques. In addition, with mechanization, the clerical worker is removed from the card retrieval process, eliminating much of the human error normally attendent non-mechanized systems. Consequently, the reliability and accuracy of the retrieval operation is increased while the probability that documents, when returned to the file, are misfiled, preventing their future retrieval, is decreased. Finally, mechanization of the card system, by eliminating the need for the filing clerk, produces long range cost savings as well as a reduction in personnel problems caused by job dissatisfaction typically associated with routine work such as filing.
In order to achieve the advantages of mechanized card storage and retrieval, U.S. Pat. No. 3,536,194, entitled Document Retrieval and Handling System, discloses a system in which documents are randomly stored in containers located at addressable stations, and from which documents are automatically retrievable and returnable, either selectively or in bulk. In such patent, a storage and retrieval system is disclosed having a pair of spaced, parallel storage racks, each having a plurality of individually numbered and addressable storage compartments arranged in a 50 column by 20 row matrix configuration. Normally positioned in each of the numbered storage compartments is a container or cartridge holding up to 100 randomly arranged cards, each of which is code notched along its lower edge to permit digital addressing for selecting a card from a deck of cards stored in the cartridge.
Also included are one or more receiving stations for selective retrieval of cards from a cartridge. Each receiving station is positioned behind the rack in line with an access port which, in practice, is an empty storage compartment. Associated with the storage compartments and the access ports is a carriage assembly which travels in the space between the racks for transferring cartridges between the access ports and the numbered storage compartments. The carriage assembly includes a transport mechanism for moving cartridges between it and any one of the storage compartments.
A cartridge transporting device is also provided for transporting cartridges between the storage compartment used as the access port and the cartridge receiving station. The system further includes a gate assembly which provides a mechanical stop for the cartridge after transit from the receiving station into the access port. The gate includes a sensor which signals the control system that a cartridge has been delivered to the access port for delivery to the carriage assembly.
The present invention is concerned with that portion of the above described document storage and retrieval system responsible for moving cartridges between the receiving station and the carriage assembly. That is, and as described more fully in the above-mentioned patent, in order to conduct a card carrying cartridge into one of the storage racks for storage therein, a transport mechanism is required for moving a cartridge from the receiving station onto the carriage assembly. The physical design of the card storage system necessitates the use of at least one storage compartment to function as an access port. Accordingly, the transport assembly conducts the cartridges from the receiving station into this storage compartment. It has been found necessary to provide a retractable mechanical stop to insure that this transport assembly does not project the cartridge beyond the access port where it might be contacted by and injure the carriage assembly as it moves into position adjacent the access port. It has also been found necessary to provide a sensor for advising the operator that the cartridge is in position in the access port, ready for delivery onto the carriage assembly. With the arrival at the access port of the cartridge carriage, which eventually transports and injects the cartridges into their respective storage compartments, the stop is retracted by its electromechanical mechanism to allow the carriage assembly transport mechanism to pull the cartridge from the access port onto the cartridge carriage.
As stated previously, the physical design of the above-described card storage system necessitates the use of storage compartments for installation of the transport and gate assembly. Therefore, all pockets so used reduce the number of available storage compartments for cartridges and, consequently, the number of cards stored by the possible magnitude of 100 cards per cartridge and 1 cartridge per pocket. This being the case, the number of storage compartments used for the transport and gate mechanism should be minimized. In spite of this, the document retrieval and handling system described in the above-mentioned patent had separate transport and separate gate mechanisms and used 5 pockets for an installation of one access port.
That is, in addition to the access port, the gate mechanism was positioned in the storage compartment immediately thereabove and the connection of the gate mechanism to the storage rack also resulted in use of the storage compartment above it. The transport mechanism was positioned in the storage compartment below the access port, and its mode of connection to the storage rack required use of the storage compartment below it. Thus, each receiving station would require the use of 5 storage compartments, reducing the number of cards that could be stored by 500. Certain system configurations contained as many as 4 receiving stations, requiring 4 access ports, and reducing the number of available storage pockets by 20, corresponding to 2,000 cards. Furthermore, the mechanically actuated electrical switches on the previous gate assembly, which were required to determine the presence of a cartridge in the gate, were extremely delicate and sensitive to switch actuation adjustment.